Fix typos mostly in comments, docs and test names (GH-15209)

diff --git a/Lib/test/test_wsgiref.py b/Lib/test/test_wsgiref.py
index bce3329..6af4514 100644
--- a/Lib/test/test_wsgiref.py
+++ b/Lib/test/test_wsgiref.py
@@ -586,10 +586,10 @@
         expected.update({
             # X doesn't exist in os_environ
             "X": "Y",
-            # HOME is overriden by TestHandler
+            # HOME is overridden by TestHandler
             'HOME': "/override/home",
 
-            # overriden by setup_testing_defaults()
+            # overridden by setup_testing_defaults()
             "SCRIPT_NAME": "",
             "SERVER_NAME": "127.0.0.1",